Hosmer Allen Johnson was born on October 22, 1822 in the small town of Wales outside of Buffalo, New York. He spent his childhood playing in a large hill range near his home, and it was this outdoor exploration that led him to select a scientific profession as well as to study nature for recreation. At about twelve years of age, his family moved to Almont, Michigan, where he worked on the family farm. During this time he succumbed to an attack that left him with a permanent bronchial tube irritation, which left him susceptible to repeated attacks of pneumonia for the rest of his life.

In 1841 he entered into an academy in Romeo, Michigan, where he prepared for college. Following this, he entered the University of Michigan, from which he graduated in 1849. Three years after receiving his degree of AB, he received the degree of AM, and at a later period, that of LLD.

After graduating Dr. Johnson went to Chicago and continued his study of medicine under Professor Herrick. In 1851 he became the first Intern of Mercy Hospital, and in 1852, he graduated from Rush Medical College. In 1853 he became a member of the faculty at Rush and worked there until his resignation in 1858. Shortly after leaving Rush, he took part in the founding of the Chicago Medical College, in which he was a professor and trustee until his death. He was also first President of the Faculty. During this time he was editor of the North Western Medical Journal and a member of the City, State, and National Boards of Health.

During the Civil War, he was commissioned as one of the Board for Examining Surgeons and Assistant Surgeons for the Illinois regiments, and it is said that as member and president of this board, he examined over one thousand physicians. He retained this spirit of service later in life. After the Great Chicago Fire, Dr. Johnson was one of the chief managers of the Relief and Aid Society, which distributed millions of dollars of property among those affected. Besides these appointments, he also served as an active member of the Chicago Academy of Sciences, the Chicago Historical Society, and the Astronomical and Microscopical Societies. He was not much of a contributor to medical literature, but he was known as a consistent and efficient supporter of measures for the advancement of medical education and of the public health.

NOTABLE FACT: Dr. Johnson had quite an ear for languages, studying Latin, Greek, Hebrew, French, German, Italian, and Spanish. In his boyhood he also picked up a considerable practical knowledge of the Ojibway language from surrounding native peoples.